The grant supports studies on the renin angiotensin aldosterone system in health and disease. Studies are being conducted on a group of 275 normal volunteers and 275 patients with mild essential hypertension. Measurements are made on sodium excretion, plasma renin activity, plasma aldosterone, renin substrate, angiotensin I and angiotensin II levels. Repeat studies are being done on the hypertensives after an interval of 12 to 18 months to test reliability of 'renin profiling' and the influence of treatment on the renin profiling. The project includes a study of the optimal means of sampling renal venous renin and the conditions which ensure the most reliable interpretation of these data as a definitive means of diagnosis of renovascular hypertension. Reliability will be judged on the basis of accuracy of predicting favorable results from surgical correction. In addition, the factors controlling aldosterone production in the absence of a functioning renin-angiotensin system (the anephric state) are being studied. The relative importance of Potassium and ACTH in this state is the main objective of this portion of this research project. BIBLIOGRAPHIC REFERENCES: Whelton, P. K., Russell, R. P., Harrington, D. P., White, R. I., and Walker, W. G.: The importance of renin in post-transplant (single kidney). Hypertension. Presented Amer. Soc. of Nephrology. Ninth Ann. Mtg. Nov. 21st to 23rd, 1976. Mitch, W. E., Whelton, P. K. Cooke, C. R., Walker, W. G. and Maddrey, W.: Hepatic renin and aldosterone extraction in alcoholic hepatic disease: Effect of prednisolone therapy. Clin. Res., 1977, 25:315A.